Reciprocating piston internal combustion engines are well known in the art and typically operate in either a two cycle or a four cycle mode. In a two-cycle mode of operation, each downward stroke of the piston supplies power to a rotating crank shaft. During the downward stroke, burned gases are exhausted and fresh fuel and air are drawn into the combustion chamber. As the piston subsequently moves upwardly in the cylinder, the exhaust port is closed and the fresh fuel/air mixture is compressed and ignited.
In a four-cycle mode of operation, each piston delivers power to the crank shaft every two strokes. The explosion of the fuel/air mixture in the combustion chamber forces the piston downwardly to deliver power to the crankshaft. As the piston passes bottom dead center and begins to rise in the cylinder, the burned gases are forced out through an exhaust valve or port. After passing top dead center, the downward movement of the piston draws a fresh charge of fuel/air into the cylinder which is compressed and ignited during the following upward stroke of the piston.
The increasingly stringent requirements regarding exhaust emissions of internal combustion engines have necessitated the use of means to precisely meter the amount of fuel and the amount of air mixed in the combustion chamber to achieve a fuel/air ratio as close to stoichiometric as possible. Fuel injection systems have virtually replaced the carburetor, since they are capable of more precisely metering the amount of fuel entering the combustion chamber.
It is known to utilize pressurized air to mix with the fuel in the combustion chamber. The air may be either from a reservoir of compressed air, or may be pressurized by use of a turbocharger or supercharger. The turbocharger is a rotary impeller connected to a turbine that is driven by the exhaust gases from the engine. The supercharger usually comprises a rotary or screw-type air pump driven by a power take off from the engine crankshaft. Typically, the superchargers are vane-type compressors or screw-type compressors.
Although, these systems have proven generally satisfactory, the use of turbochargers or superchargers has increased the complexity of the typical internal combustion engine to the point where its reliability is inherently compromised.
Additionally, in a turbocharger there is a certain amount of time lag between the opening of the throttle valve and the delivery of pressurized air to the combustion chamber. This is caused by the amount of time it takes the exhaust gases to increase the rotation of the turbine/impeller to pressurize the incoming air.
The supercharger, since it is driven through a mechanical connection to the crankshaft does not suffer from "turbo lag". However, the drive systems for superchargers, usually belt drives, increase the complexity of the engine and do not provide a mechanically foolproof interconnection between the crankshaft and supercharger.